The present invention relates to a protective cover and packaging method for multiple memory chips on a circuit board.
In the field of memory modules, memory chips are typically individually encapsulated in a protective package to protect the chip surface because it is susceptible to mechanical damages. In addition, the memory chips are interconnected to a circuit board through the use of leads, providing a secure interconnection between the chips and the circuit board.
Recently, however, the memory chips of memory modules are not individually encapsulated. Rather, the surfaces of the chips are exposed. As a result, leads are not used to interconnect the chips to the circuit board. In place of the leads, alternative techniques are used to interconnect the chips and the circuit board, which are typically more fragile than conventional leads.
As a result, the interconnection between the chips and the circuit board is very fragile and susceptible to mechanical damages. Therefore, there is a need for a protective packaging for memory chips to protect the exposed surface of the chips, and to protect the fragile interconnection between the chips and circuit board.
In addition, new memory devices, such as Rambus(copyright) RDRAM memory devices, allow the separate memory chips of the module to have varying functionality states (e.g., active, active/idle, standby, nap or inactive.) As a result, the separate chips of a module may consume varying amounts of power and therefore generate varying amounts of heat. Moreover, the different amounts of heat generated by the separate chips will change dynamically in a time dependent fashion.
For example, a first chip may generate more heat when it is in an active state, and sometime later may generate less heat when in an inactive state, while a second chip on the module generates more heat. As a result, there is a further need for a protective multi-chip memory module packaging that is able to dissipate heat from the chips of a memory module, wherein the separate chips generate varying amounts of heat, which changes dynamically among the chips.
Furthermore, the chips within a multi-chip memory module may have varying height tolerances. Therefore, the protective packaging should also accommodate for the potential variances in the height among the multiple memory chips of a memory module.
The present invention provides packaging cover to encapsulate a board having multiple separate chips, wherein the separate chips dynamically generate varying amounts heat.